Personally I think people who read Op-Ed sections of newspaper have probably already made up their mind who to vote for.
But I think the trend of many newspapers switching from '00 Bush endorsements to '04 endorsements is significant in another way.
Consider that these editorial boards are made up of 7 (or so) individuals who choose between the candidates, with the majority winning (except at the Plain-Dealer, but that's another story).
A switch from Bush to Kerry means at least one of those people changed his/her mind, changing a 4/3 Bush vote to a 4/3 Kerry vote. Or possibly the swing was much bigger than that. It's possible all 7 board members made the switch.
Continued below...
We're seen about 20 newspapers make the switch already, and 2 flip from Gore to Bush. That means -
at a minimum - 91% of people who changed their vote changed from Bush to Kerry. And when you consider that even the pro-Bush editorials have been bashing him on many issues, I'm guessing he's lost individual support at those papers as well.
These informed individuals represent a lot of other people in the country. These endorsements can be viewed as a poll of sorts (100 endorsements equals 700 people equals a pretty good sample size, if not a demographically appropriate one), and the poll is telling us that conservatives are jumping ship.